This invention relates generally to on-board weighing systems for vehicles, and more particularly concerns an on-board weighing system for use with a front loader-type refuse vehicle.
Front loader refuse vehicles are generally well known. In such refuse vehicles, a refuse container is lifted by a fork and lift arm arrangement from a position in front of the cab up over the cab of a truck, depositing the refuse in the container in a truck body portion located immediately to the rear of the cab.
As with many refuse vehicles, it is important to accurately ascertain the weight of each load of refuse so that the customer can be appropriately billed and so that the truck will not be overloaded. Historically, customers were billed by volume. Only recently have attempts been made to weigh refuse picked up and then to adjust service frequency and/or charges accordingly. Such on-board scale weighing systems, however, need to be accurate, durable and cost-effective. Sensors have been placed on various portions of the lift assembly and under the truck body. Some systems have been sufficiently accurate, but not very durable or too expensive, while others have been durable but not accurate enough for small pickup weights. Still others have been inexpensive but have lacked durability and accuracy.
It is desirable that the accuracy of such systems be within 20 pounds or 1% of the true pickup weight of the refuse. Some attempts have been made to improve accuracy by placing the sensors on the extending forks which go underneath the refuse containers for front loader vehicles. This is a generally desirable position, relative to accuracy, but the sensors are susceptible to damage when mounted on the forks and the weight recorded by such systems may depend on the position of the container on the forks. Correction of the output signal from the sensors to account for the differing sizes of the containers and the position of the containers on the forks is necessary in such cases.
Also, the forks themselves are often subject to extreme conditions of use which can negatively affect accuracy of weighing systems mounted thereon. For example, the forks themselves are often used to dislodge containers frozen to the ground, or to reposition a fully loaded container.
Hence, it remains a difficult challenge for a front loader weighing assembly to be highly accurate, consistent in results regardless of the position and/or size of the container, and sufficiently rugged to withstand the rigors of ordinary use.
Accordingly, the present invention is an on-board weighing system for front loading vehicles which includes: front loader assembly for vehicles, including two spaced fork members upon which the load to be weighed is positioned, the fork members being secured to a cross-member which is supported in the vicinity of the respective ends thereof by lift arms which are mounted on the vehicle and which move the load into the vehicle; and load sensor means for monitoring deflection in sensing sections in each fork, the sensing sections including a plurality of flexure means therein, the flexure means being staggered in length across the sensing section.